1. School of Pharmaceutical Sciences, Guizhou University, Guiyang, P. R. China
2. Guizhou Engineering Laboratory for Synthetic Drugs, Guiyang, P. R. China
3. Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing, P. R. China
4. Key Laboratory of Guizhou for Fermentation Engineering and Biomedicine, Guiyang, P. R. China